Emily Chan
In 1972, a pregnant woman had her blood sampled, and doctors realized that it was missing a surface molecule found in all other red blood cells at the time.
Now, scientists have solved the 50-year-old mystery of the molecule’s strange absence. Researchers from the United Kingdom and Israel have described a new blood group system in humans.
“It represents a huge achievement, and the culmination of a long team effort, to finally establish this new blood group system and be able to offer the best care to rare, but important, patients,” said Louise Tilley, a U.K. National Health Service hematologist, who has been researching the phenomenon for almost 20 years.
The two best-known blood group systems are ABO and the rhesus factor. However, humans actually have several different blood group systems based on the cell-surface proteins and sugars in our blood cells. These antigen molecules are used to identify familiar and foreign substances within the body.
But if these identification markers do not recognize a foreign substance, such as a blood transfusion, the tactic that is meant to be life-saving can cause severe reactions or even be fatal.
The majority of major blood groups were identified in the early 20th century. Since then, many blood groups that have been discovered only affect a small number of people. This is also the case for the new blood group.
It was a challenge to carry out the research because genetic cases were so rare. Previous studies have found that over 99.9 percent of people have the AnWj antigen that was missing from the patient’s blood in 1972.
The antigen lives on a myelin and lymphocyte protein, which led the researchers to call the new system the MAL blood group.
A person can end up with an AnWj-negative blood type when they have a mutated version of both copies of their MAL genes.
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